using dc current with magnets

[tigster]

i have not yet used magnetic holders with welding projects, but plan to real soon. on one package i saw a warning not to use dc current when welding. does this make the arc wander, and if so, how bad? is it better or worse with mig or stick? thanks.

[Hotfoot]

I don't know about DC, but they affect the arc on AC and MIG very notably. I use them only for initial positioning until I can put some tack welds down,m then I remove them ASAP...Plus, they annoy the heck out of me by attracting all the metal grindin's.

[1990notch]

I've noticed arc problems with tig as well. I think a better solution for 90 degree angles is one of those angle clamps. Not the piece of junk ones that HF sells for $15 (ask me how I know they're junk), but a good one. It seems like it should be fairly easy to make one out of some large angle iron and some plate. Could even use aluminum to make it easier to handle.

[Rocky D]

They don't effect MIG much, but you will notice a the arc wander in TIG and stick when you weld too close to the magnetic field.
There is a mag unit that will attach to an automatic TIG torch to cause the arc to wag back and forth, helping to widen the weld bead. We called it a "wiggler".

[tansit234]

Used to be on big contactors (relays) they would use magnets to blow out the arc and save the contact pad. Its still done too, its called a mag blow out. Anyways with my mig if I get a magnet real close to the arc it will snuff it or push the arc away, other times it will send the filler in the wrong direction. I only ever used a magnet close to the gun once for a tack on a very small part. Took double everything including time.

[Rocky D]

I s'pose a lot would depend on the strength of the magnet.